Although brain monoamines serotonin, noradrenaline, and dopamine have been repeatedly shown to be linked to depression, it remains unclear how monoamine dysfunction is mechanistically related to symptoms of depression. We hypothesized that imbalances in the networks of regions innervated by monoamines disrupt patients' learning and decision-making abilities, and this disruption could, in turn, lead to symptoms of depression. We have conducted functional magnetic resonance imaging (fMRI) studies on learning and decision-making, mainly focusing on the role of serotonin. Our results suggest that parallel organization for reward prediction at different time scales in the striatum is under differential modulation by serotonin, and that depression is associated with a diminished recruitment of the dorsal striatum, involved in long-term reward prediction. Based on these findings, the brain mechanisms of depression are discussed.
<Authors' abstract>
Brain Mechanisms of Depression -Preliminary Evidence from fMRI Studies-
1 Department of Psychiatry and Neurosciences, Hiroshima University
2 The Department of Mechanical Engineering, the University of Tokyo
3 Department of Neurology, Shimane University
4 Department of Psychology, School of Human Sciences, Senshu University
5 Department of Cognitive Neuroscience, ATR Brain Information Communication Research Laboratory Group
6 Neural Computation Unit, Okinawa Institute of Science and Technology Graduate University
2 The Department of Mechanical Engineering, the University of Tokyo
3 Department of Neurology, Shimane University
4 Department of Psychology, School of Human Sciences, Senshu University
5 Department of Cognitive Neuroscience, ATR Brain Information Communication Research Laboratory Group
6 Neural Computation Unit, Okinawa Institute of Science and Technology Graduate University
Psychiatria et Neurologia Japonica
116: 825-831, 2014
＜Keywords：depression, fMRI, reward prediction, serotonin, striatum＞
